The present invention relates to an endoscope shaft in accordance with the preamble of claim 1.
Endoscopes are instruments especially for exploring hollows or tube-shaped conduits of the body, for instance for medical purposes. Endoscopes of this kind are preferably used for exploring the esophagus, the stomach, the duodenum from the stomach, the intestine from the anus, the urethra, the vesica and the ureter. Endoscopes are mostly equipped with a lighting device at their front end and with an optical system for visually detecting the area of the body hollow or body canal located forward thereof.
Further endoscopes usually comprise a working conduit or channel as it is called through which various working instruments can be introduced and operated, e.g. forceps for taking tissue specimens, biopsy needles, heated cutting wires, small scissors or the like. Finally, as a rule functional conduits, for instance a fluid conduit for wash and operating wires for bending the front end of the endoscope in various directions are provided. Altogether the endoscope has, apart from its rear operating end and a connecting rope, an elongated flexible bar shape. The common outer diameters approximately range from 9 to 15 mm and are somewhat more at the front head.
So far endoscopes have been introduced into the body in that the physician pushes the pressure-stiff endoscope and/or the pressure-stiff endoscope shaft into the body from the part of the endoscope protruding from the body. This way of introducing the endoscope is particularly difficult and time-consuming especially in the case of the coloscope, as in the latter case the intestine has bends and frequently isthmuses. Accordingly, coloscopic examinations have been costly examinations which are unpleasant to the patient so far and therefore are hardly taken into account for a wide-spread application. Moreover the handling of a coloscope requires a physician experienced in this matter.
Furthermore the prior art has shown that endoscopes of the known construction represent extremely complicated and thus cost-intensive designs due to the stiffness required for inserting them into the patient""s hollow to be examined and at the same time the necessary flexibility. These constructions are so expensive that they have to be employed again and again. Therefore it is necessary to take costly sterilizing measures after each examination, wherein there is finally also a risk of damaging the endoscope shaft, especially when such sterilizing operations are carried out by an untrained staff.
In view of this situation, it is the object of the invention to provide an endoscope shaft which can be manufactured in a considerably less expensive way and in which the risk of damaging, for instance during sterilizing operations, is eliminated.
This object of the invention is achieved by an endoscope shaft comprising the features of claim 1.
The invention is based on the following consideration:
An endoscope of this species is known from prior art, especially according to DE 42 42 291 A1. This endoscope substantially consists of an endoscope head, or a distal end, to which an endoscope shaft made of a flexible yet push-stiff tubular body is connected and an operating device at the lower end of the endoscope shaft. The operating device includes a number of actuating wheels rotatably mounted on the endoscope shaft which are operatively connected with the distal end through operating wires or Bowden wires movably laid within the endoscope shaft.
For introducing this endoscope shaft into the intestine of a patient to be treated, for instance, this prior art makes use of a kind of double reversing hose system, as it will be briefly described hereinafter:
The double reversing hose system known from this publication provides to slidingly guide the endoscope shaft in a two-sided reversed hose which in turn is movable by a drive means acting on the inner hose portion of the reversing hose which is formed hereby. The drive means includes at least a continuously driving feed means, for instance a number of drive wheels, which can be radially forced onto the inner hose portion to move the latter substantially continuously in axial direction of the shaft. This has the advantage that the continuous advance of the reversing hose system can be exactly controlled and thus the distal end of the endoscope, for example, can be guided exactly to the point.
Here it is provided that the pressing force of the feed means acting on the inner hose portion is selected so that the shaft is in direct frictional contact with the inner hose portion at least in the area of the feed means. The feed means is constituted by one or more frictional wheels, as already indicated in the foregoing, which can be biased against the inner hose portion at a predetermined or adjustable pressing force so that a continuous and as slip-free as possible feed of the endoscope shaft into a patient""s hollow is ensured. The endoscope shaft itself forms the abutment of the frictional wheels.
Moreover the drive means includes a device for synchronizing the movement of the shaft with the movement of the reversing hose. This may be a rear and front end or clamping piece axially fixed to the shaft to which the rear or front reversing portion of the reversing hose depending on the direction of feed is glidingly adjacent so that the reversing hose applies a braking force to the shaft via the rear or front end piece inversely to the currently prevailing feed force. Alternatively to that, the synchronizing device can be a roller or spindle drive acting on the rear end portion of the shaft which is synchronized with the reversing hose drive such that the rate of feed of the shaft is half of the rate of feed of the inner hose portion.
The substantial advantage of the endoscopic apparatus known from DE 42 42 291 A1 consists in the fact that the endoscope shaft is cased over the total length thereof except the front movable distal end portion by the drive means, i.e. the double reversing hose system, and thus does not directly contact the wall of the hollow space. Moreover the double reversing hose system creates a kind of self-propelling, whereby no more feed forces have to be applied to the endoscope shaft from the operating end thereof.
Hence DE 42 42 291 A1 and the technical teaching given there establishes the precondition for forming novel endoscope shafts as they are now the subject matter of the invention.
Consequently, it is the gist of the invention according to claim 1 to provide the endoscope shaft consisting of a hose body which forms a central working conduit and a number of functional conduits with a silicone shell which coats the outside of the above-characterized hose body and thus forms the outer layer of the endoscope shaft. The hose body itself constituting the core of the endoscope shaft consists of an extruded synthetic material.
It has turned out that this structure can be manufactured at especially low costs, because no flexural strengths in the longitudinal direction of the shaft have to be taken into account when employing such a shaft with a drive means in the form of a double reversing hose system of the known design, for instance. Extruded plastic sections are extremely inexpensive, wherein the silicone shell can simply be cast around the extruded hose body.
This structure can be manufactured so inexpensively that the endoscope shaft according to the invention can be used as a disposable rendering sterilizing measures superfluous.
Moreover the silicone shell acts like a soft cushion protecting the hose body against damage in the case of impact. It has further turned out that the silicone shell is suited, despite its highly elastic soft characteristic, as an abutment for a drive means known from prior art, for instance the above-described reversing hose drive system.
Further advantageous embodiments of the invention are the subject matter of the other subclaims.